Effects Of Wetland Restoration On Benthic Fauna And Its Environmental Factors

Macrozoobenthos play an important role in the process of material circulation and energy flow in wetland ecosystem. Wetland restoration has the different effect on the community structure of Macrozoobenthos. Studies were conducted on the differences of benthic community structure, diversity and dynamics of benthic communities and ecological factors of benthic habitats such as the index of heavy metal amount and eutrophication degree of Hg, Cd, As, Cu, Pb, Cr and Zn in different stages of wetland restoration and non-restoration areas in order to explore the effect of restoration on the Macrozoobenthos community of wetland and its mechanism in the Da Wenliu Management Station of Yellow River Delta Nature Reserve in spring,summer and autumn in 2015, The results are as follows.(1) We collected 33 species of macrozoobenthos belonging to 3 phylums, 24 families and 25 genera, in which 15 species of insects were most abundant,accounting for 46.9% of the total species. 5 species of Oligochaete, accounting for15.6%, and 4 species of Gastropoda, accounting for 12.5%. There were 2 species of Polychaete, Hirudinea, Crustaceans and Arachnida respectively, accounting for 6.1%respectively of the total. Only 1 species Myriapoda which was least of the total species, accounting for 3.0%. The dominant species were Pheretima Tschiliensis,Bullacta exarata, Parafossarulus striatulus, Chironomid larvae B and Perinereis aibuhitensis. The average biomass of benthic animals was13.56g·m-2 and average density was 1113.56ind·m-2. Compared with the previous reports, both species and diversity of the collected benthic animals decreased.(2) Hg,Pb and As were the main pollution heavy metals in research areas because their average amount were slightly higher than that of other heavy metals.The degree of heavy metal pollution in spring was greater than in summer, and the greatest was in autumn. The heavy metal pollution degree was greater in late restoration area than that in early restoration area, and the greatest was in non restoration area. In addition, there was a significant correlation among heavy metal elements.(3) The quality of the water in restoration areas was in the state of the medium nutrient level, while that in non restoration area was medium eutrophication.(4) There was significant positive correlations between the density of Oligochaete and most of the heavy metals with the exception of Cr, and therefore Oligochaete could be indicative species of heavy metals pollution in wetland.(5) Biomass of macro-zoobenthos had significantly positive correlation with active phosphorus concentrations(P < 0.05), Shannon Wiener diversity index H was positively correlated with chemical oxygen demand of water, soil salinity(P < 0.05),while species diversity index H and species abundance index d were negatively correlated with water depth and nitrate nitrogen concentration(P < 0.05) respectively.(6) The environmental quality in restorated area was significantly higher than that of nonrestorated area, which indicated that the restoration work in the early stage had a significant effect in research area.